When I was in the Chicago area, I was at a suburban car show where a Pace Car Replica was displayed that looked exactly like the box model. In fact, he had the model box on his back seat. The car had the 396 375HP engine and 4 speed as well. In chatting with him, he claimed his car was the prototype that Revell/Monogram photographed for the model. Took him at his word. He had removed the smog control system.

My 1968 Z28 (and 1970 Z28) came with the A.I.R. system. In fact, on the 1968, the optional headers also had the bungs for the connectors.

I like to make to make my models look as real as possible. Obviously, the quality of any kit makes compromises necessary. Scale is also a factor. At some point, you need to back off or the detail may overwhelm the result, particularly in the engine bay. That's where the technique of Tromp L'oeil (Fool the eye) can be effective. For those familiar with the subject, the mind's eye can fill in some detail.